NEWBORN HEARING SCREENING

“There are 5-6 infants who are hard of hearing out of 1000 neonates.” – Garg et.al (2015)

HOW DO WE HEAR?

Sound waves originating from any source are initially received by the outer ear. Thereafter, the sound waves after hitting the eardrums are directed towards the inner ear via three tiny bones in the middle ear known as ossicles. The inner ear sends out these sound signals to the auditory centre in the brain via auditory nerve, where they are processed. This helps us to hear.

HEARING LOSS IN ELDERLY

According to WHO, Adult-onset hearing loss ranks 2nd in the leading causes of Years Lived with a Disability (YLD).

What Is Hearing Loss?

Hearing loss or hearing impairment is the inability to hear partially or totally in one or both the ears. It occurs when the sensitivity to the sounds generally heard is diminished. The severity of hearing impairment can be determined based on the amount of increase in volume above the normal volume necessary before the person can actually hear it. It can be temporary or permanent, depending on the severity of the hearing loss. If it happens to children, then it may cause speech and language learning difficulties, and if it occurs to adults, then they might have work related problems and their quality of life might get affected as well. However, in the older people, hearing loss can cause loneliness and social isolation.

We are regularly exposed to various types of sounds, which are surfacing every now and then. Our ears, small but powerful sense organs, are continually receiving these sound waves and sending them across to the brain, letting us hear clearly and feel the sound effects. However, we fail to understand the supreme importance of hearing in our lives and society and that our ears are indeed priceless assets!

Threshold of Hearing

Generally, sound is indicated by ‘frequency’ and ‘intensity’. In ‘frequency’, our ears can generally hear between 20 to 20,000 Hertz. Sounds less than 20 Hertz are termed as ‘hyposonic’ and those over 20,000 Hertz are known as ‘hypersonic’ sounds. Similarly, when someone is able to hear and understand sounds of the least intensity, it is termed as ‘hearing threshold’ or ‘threshold of audibility.’ Generally, sounds stronger and intense than .0002 dym/cm create hearing sensations in humans and taking this as a reference, the unit of measuring sound intensity can be cited as decibel (dB).

Generally, when the hearing threshold or the least hearing ability of a person hovers between 0-25 dB, then he/she can be termed as gifted with normal hearing. However, when hearing threshold or the least hearing ability is over 25 dB, then it can be termed as hearing loss or impairment.

Degree of Hearing

Check out the following gradations of hearing loss according to varied thresholds and the degree of hearing loss:

0-25 dB

Normal hearing

26-40 dB

Mild hearing loss

41-55 dB

Moderate hearing loss

56-70 dB

Moderately severe hearing loss

71-90 dB

Severe hearing loss

91 dB

Profound hearing

Ears are ‘hearing machines’ of humans.

How we hear?

Human ear can be functionally divided into 3 main sections:

Outer ear

Middle ear

Inner ear

Sound waves originating from any source are initially received by the outer ear. Thereafter, the sound waves after hitting the eardrums are directed towards the inner ear via three tiny bones in the middle ear known as ossicles. The inner ear sends out these sound signals to the auditory centre in the brain via auditory nerve, where they are processed. This helps us to hear.

Any problem with normal transmission of sound waves to the auditory nerve or these three areas, results in hearing impairment or hearing loss.